Reinforcing device of a folded package for convex objects

ABSTRACT

The device is constituted by rectangular reinforcement pieces made from a strip of semi-rigid material, fixed on a thin flexible sheet on the median portion of the zones and mutually articulated by hinges located astride the folds separating the zones.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a 35 U.S.C. 371 application of PCT/FR97/00923 filedMar. 27, 1997.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a reinforcing device of a package forconvex objects, which package is made from a folded thin sheet, thefolds of which are fixed at their ends so as to impart to it resistanceto vertical load.

2. Description of the Related Art

A package for convex objects, which is made from a thin, flexible sheetwhich, in one of its applications, makes it possible to eat a roundsandwich leaving the package around the sandwich in order to collect anyruns and to fold it over as the sandwich is eaten, is known from patentsFR-A-2595666 and FR-A-2628719. The flexibility of the sheet makes itpossible to unfold manually the folds around the convex object; indeed,during unfolding of the folds with one hand, the other hand holds theconvex object by gripping it between the fingers; the more flexible thefilm, the less need there is to grip the convex object to hold itbetween the fingers; when this convex object is fragile like, forexample, sandwiches of an essentially cylindrical shape generated byrevolution which are produced in fast-food catering and made frombrioche-type bread, there is a risk of crushing the sandwich duringunfolding of the folded package; the counterpart of the flexibility ofthe sheet used is that the package does not protect the sandwich againstcrushing during transport. This shortcoming led to the idea ofprotecting the sandwich, when it is of cylindrical shape, with a boardring which surrounds it over its entire lateral wall, the whole thenbeing surrounded by a thin sheet of paper. The disadvantage of such adevice is that its implementation is very time-consuming and that, whenit is associated with the folded package as described in the patentFR-A-352676037, it is difficult to remove the board ring withoutremoving the folded package which, therefore, no longer performs itsfunction of protection against runs. Within the scope of development ofthe folded package, attempts were made to fix the reinforcing stripdirectly to the thin sheet in the direction perpendicular to the folds;but the thickness of the reinforcement is limited after a short timebecause it soon becomes impossible to unfold the reinforcement withoutcrushing the sandwich. To overcome this difficulty, an attempt was thenmade in the patent FR-A-2734791, while retaining a reinforcing stripfixed to the sheet, to leave it pre-unfolded with equal folds while thefolded part of the package is folded as described previously; theproblem is that, when it is associated with a flat sheet, as in thepatent FR-A-2676037, which makes it possible to protect the upper andlower openings left by the edges of the folded part, it is no longerpossible to stack them appropriately so as to reduce the volume theyoccupy during transport of the folded package.

BRIEF SUMMARY OF THE INVENTION

The object of the invention is to produce a device which makes itpossible to obtain a folded package which has good resistance tovertical load and is easy to unfold and easy to store when it is foldedup for transport.

To this end, rectangular reinforcements originating from a strip ofsemi-rigid material, which are cut, positioned and fixed usingappropriate means, are associated with the successive zones separated bya fold.

The invention also relates to devices for positioning, folding andfixing the reinforcing means of the package.

BRIEF DESCRIPTION OF THE DRAWINGS

In the appended drawings:

FIG. 1 shows the reinforcing device of the thin sheet constituting thepackage before it has been folded and the end of the folds has beenfixed.

FIG. 2 shows a section of the thin sheet in line with the reinforcingdevice according to FIG. 1 with the successive stages which make itpossible to fold it up.

FIG. 3 shows an exploded perspective view of the reinforcing device whenit is unfolded around the convex object (not shown).

FIG. 4 shows an exploded elevation view of the essential components ofthe device for cutting, positioning and fixing the elements constitutingthe reinforcing device according to the invention.

FIG. 5 shows a view of the main components, in an exploded elevation, ofthe device for folding the thin sheet reinforced according to the stagesin FIG. 2 and produced using the device in FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

The device consists in associating with the flexible sheet 1 (FIG. 1),instead of a continuous reinforcing strip, a discontinuous stripconsisting of rectangular reinforcements 2 positioned in proximity toone another and articulated with one another by a hinge 3 formed by thethin sheet 1 which interconnects them. As the folding consists ofsuccessive rectangular zones 5 and 6 separated from one another by folds4 forming an integral part of the hinge 3, the rectangularreinforcements 2 are positioned within these rectangular zones 5 and 6and are folded up on one another in the same manner as the folds 4 ofthe thin sheet. When the successive rectangular reinforcements 7 and 8(FIG. 2) are folded up on one another in such a manner that these twosuccessive rectangular reinforcements 7 and 8 are in direct contact, itis necessary that the distance 9 that separates them is greater than orequal to their combined thickness 10 and 11, otherwise the portion ofthin sheet serving as a hinge 12 is subjected to tensile stress whichmay either prevent the positioning of the rectangular reinforcements 7and 8 on one another or cause stretching or tearing of the part of thinsheet forming the hinge 12; on the other hand, when the fold 13 is madein such a manner that it is the thin sheet 14 which is in contact withitself and the rectangular reinforcements 8 and 15 are positioned on theouter side, they may be positioned one against another.

The positioning of the rectangular reinforcements 2 (FIG. 1) in relationto one another is one of the main problems solved by the device formingthe subject of the invention, making it possible to position therectangular reinforcements 2 correctly in relation to one another. Theserectangular reinforcements 2 (FIG. 3) have a height 16 consistent withthe height of the convex object to be protected and in particular, byway of non-limiting example, of the sandwich of essentially cylindricalshape generated by revolution described above; when the package producedin this manner is unfolded (FIG. 3), the succession of rectangularreinforcements 2 interconnected by the hinges 17 of the flexible sheet 1constitutes a series of dihedra essentially forming a ring 18; whenvertical loads are applied to this ring 18 positioned on a horizontalplane, the buckling of the rectangular reinforcements 2 under the loadis limited by the thin sheet forming the hinge 17 being placed underhorizontally orientated tensile stress; the resistance of this ring 18is limited, among other things, by the resistance of the thin sheet 1which will ultimately tear under the action of the tension when the loadbecomes too great; the rectangular reinforcement 2 can then bend.

A manner of envisaging the positioning of the reinforcement rectangles 2(FIG. 4) consists in starting from a coil of semi-rigid material, thewidth of which corresponds to the height 16 (FIG. 3) of the rectangularreinforcement; this strip 19 (FIG. 4) is drawn by rollers 20 at a speedslightly slower than the unwinding speed of the strip of thin sheet 21onto which it is going to be fixed. The strip 19 of semi-rigid materialis then drawn by a support cylinder 22 rotating at a tangential speedequal to the unwinding speed of the strip of thin sheet 21; the strip 19of semi-rigid material is held on the support cylinder 22 by a system 23of suction holes or slits 24 which allow it to slide slightly takingaccount of the difference in the unwinding speed between the tangentialspeed of the support cylinder 22 and that of the strip 19. The supportcylinder 22 serves as an anvil for knives 25 which are integral with acutting cylinder 26 and the edge 27 of which is brought to be tangent tothe support cylinder 22 along its generating lines. The position of theknives 25 on the cutting cylinder 26 and its speed are determined so asto cut rectangular reinforcements 2, the width of which is such thatthey are adapted alternately to the width of each of the thin sheetzones 5 and 6 (FIG. 1) separating two successive folds 4 of the packagewhen it is folded.

In general, the tangential speed of the edge 27 (FIG. 4) of the knives25 is equal or close to the tangential speed of the support cylinder 22according to the degree of wear of the knives 25; in any case, thepoints of contact of the edge 27 of the knives 25 on the surface of thesupport cylinder 22 are always in the same places, the suction holes orslits 24 serving to hold the rectangular reinforcements 2 being situatedbetween these points of contact. Taking account of the difference inspeed between the strip 19 and the surface of the support cylinder 22,as soon as the rectangular reinforcement 28 is cut, it is drawn at thespeed of the support cylinder 22 and a space is thus created between twosuccessive rectangular reinforcements 28 and 29. The strip consisting ofa thin sheet 21 can then be brought to be tangent to the supportcylinder 22 in the area containing the rectangular reinforcements 30which are applied accurately to the thin sheet 21 and fixed theretousing known means; then, the suction is turned off at the holes or slits24 of the support cylinder 22, which held the rectangular reinforcements31 in place, and a thin sheet equipped with rectangular reinforcementsas shown by FIG. 1 is released. It is then possible to proceed to thefolding.

In a preferred embodiment of the invention, the folding takes placeaccording to a process deriving directly from European Patent 0 528 920;the zones 5 and 6 located on either side of a fold 4 have widths A 32and B 33 with A>B; the zones have a width of A 32 and B 33 alternately;the zone 34 (FIG. 2) of width A 32 is divided into a zone 35 of widthA-B 36 and a zone 37 of width B 38; these two zones 34 and 35 areseparated by a fold 39, the two zones 37 and 41 of width B 38 and 33being located side by side; the rectangular reinforcement 40 comprises acut in line with this fold 39; the cut in the rectangular reinforcement40 (FIG. 4) of width A is made on the support cylinder 22 by a secondcutting cylinder 42; as the rectangular reinforcement 40 has alreadybeen separated from the strip 19 by the cut made by the cutting cylinder26, the two pieces 44 and 45 obtained by the cut 43 remain essentiallyside by side; this does not cause a problem insofar as the part 44 ofwidth A-B is situated at the front of the rectangular reinforcement 40of the zone of width A seen in the direction of movement; the cut inline with the fold 39 can also be made by knives positioned on thecutting cylinder 26; under these conditions, a space is formed betweenthe two parts of the reinforcement. The sheet 46 equipped with itsrectangular reinforcements 2 passes over a pre-shaping wheel 47 (FIG. 5)comprising teeth 48, the rectangular reinforcements 49 being situated onthe same side as the wheel 47; the zone 50 of width A-B is positioned atthe bottom of the tooth 48 and the two zones 51 and 52 of width B coverthe tooth 48 which is in the shape of an inverted V. A wheel 53 forclosing up the folds, made up of bars 54, takes the pre-shaped thinsheet with its rectangular reinforcements; the zones 55 of width A-B arepositioned at the top of the bars 54 while the two zones 56 and 57 ofwidth B are positioned in the hollow formed by two successive bars 54and 58; the rectangular reinforcements are then on the outer side of thewheel 53 for closing up the folds; when the bars 54 move closertogether, the zones 59 and 60 of width B move closer together and therectangular reinforcements are superposed on one another withoutdifficulty on account of the space (FIG. 2) left between two successiverectangular reinforcements 7 and 8 at the time of cutting, and the zones61 and 62 of width A-B are positioned side by side; it is neverthelessnecessary that the zones of width B have sufficient play when the bars63 and 64 are moved closer together in order that they can be releasedeasily on account of their rigidity. The zones 61 and 62 of width A-Bare then transferred onto the cylinder 65 for gathering the folds withthe rectangular reinforcement turned towards the latter 65, thesuccessive zones 66 and 67 of width B forming a projection, and thecorresponding rectangular reinforcements being situated on the inside ofthe projection; laying down of the folds can then be carried out withthe aid of a cylinder comprising, at the level of the rectangularreinforcements, a reduced diameter taking account of the variousthicknesses of rectangular reinforcement which are superposed on oneanother and which constitute a significant extra thickness.

A manner of fixing the rectangular reinforcements on the thin sheetconsists in making use of a rectangular reinforcement coated with a thinlayer of heat-sealing material located on the outer side 70 in relationto the support cylinder 22; the thin sheet can also be coated with athin layer of heat-sealing material on the side 69 facing therectangular reinforcement; fixing of the reinforcement is then performedat the time of application of the flexible sheet to the rectangularreinforcement by heating with hot air 68 the face of the flexible sheetopposite that which is coated.

What is claimed is:
 1. A reinforced package having a reinforcedresistance on vertical load and formed of an approximatelyannular-shaped reinforcement device of approximately constant heightwhen deployed comprising a thin sheet folded along successive areashaving a width A and B respectively with A larger than B whereby thesuccessive areas are separated by respective folds in the thin sheetcreating respective hinges and are reinforced in a median portion of thethin sheet by rectangular reinforcing pieces made of a semi-rigidmaterial and joined together by respective hinges made from the thinsheet with such reinforcing pieces being sufficiently spaced apart onopposite sides of the respective hinges.
 2. The package according toclaim 1, wherein when the package is folded adjacent reinforcing piecesare in direct contact and are spaced apart at a distance which isgreater than the respective total thicknesses of the successivereinforcing pieces.
 3. The package according to claim 2, whereinreinforcing pieces having a width A have a side parallel to the hinge ata distance therefrom which is equal to a difference of the width betweenA and B.
 4. Device for assembling the reinforced package according toclaim 1, comprising a support cylinder which rotates at a tangentialspeed for driving a strip made of a semi-rigid material and being fittedwith a suction device, a cutting cylinder having knives for cutting thestrip into successive rectangular reinforcing pieces which are placed onthe thin sheet which is unwound at an unwinding speed so as to form acomposite sheet which is kept in place on the support cylinder by thesuction device and with an unwinding speed of the strip being at a speedslightly less than the tangential speed of the support cylinder.
 5. Thedevice according to claim 4, which further includes a second cuttingcylinder for cutting reinforcement pieces having a width A on its rightside adjacent the hinge.
 6. The device according to claim 4, whichfurther includes coating either the rectangular reinforcing pieces orthe thin sheet with a hot sealing material so as to affix one to theother.